A Palestinian security officer has been killed and several other people wounded in clashes between rival Palestinian factions in the Gaza Strip. There was also a rare clash on the Israel-Egypt border.

Gunmen from the ruling Islamic militant group Hamas and security forces loyal to the rival Fatah faction exchanged fire in several parts of Gaza. Palestinian officials say trouble began when a Fatah member of the preventative security force was killed by unknown gunmen in Gaza City.

Then, three more Fatah security officers were wounded when their vehicle was attacked in a village in southern Gaza. Hamas said its fighters returned fire, after Fatah gunmen fired shots at a senior Hamas commander.

Sporadic fighting over the past few weeks is part of a deepening power struggle over control of the security forces that has raised fears of a Palestinian civil war.

International sanctions on Hamas, which seeks Israel's destruction, have aggravated tensions. The Hamas government, which assumed power nine weeks ago, is flat broke. It is three months overdue in paying the salaries of 165,000 Palestinian Authority employees, including about 70,000 members of the Fatah-dominated security forces.

Palestinian legislator Saeb Erekat believes civil war could happen.

"We haven't seen the worst yet. If we leave things the way they are, with two policies, with clashes in the streets, with this siege, with guns and no funds, we're losing," he said. "We're going to go down the road of real deterioration."

There was also a clash near Gaza, on the unfenced desert frontier between Israel and Egypt. The Israeli army says its troops were ambushed by unidentified gunmen dressed as Egyptian army officers, who stormed across the border. The soldiers returned fire and killed two gunmen. A third escaped. The area is known as a corridor for weapons and drug-smuggling by Palestinian militants and Egyptian Bedouin.